The extracellular matrix provides a complex and instructive substrate for cells in multicellular organisms. The matrix contains a multitude of proteins, some of which are structural, whereas others can further provide regulatory signals to modulate cell growth, differentiation, and migration.
In the developing nervous system, axons project considerable distances along pathways to reach their targets. Axon growth and guidance depends partially on the recognition of cell surface and extracellular matrix cues along these pathways. These compounds can play a role in when neurons grow, where neurons grow and when they should stop growing. In the cardiovascular system, the extracellular matrix can also provide signals for the development of smooth muscle for blood vessels, e.g., for angiogenesis.